The present invention relates to method and apparatus for controlling water distribution networks of waterworks to the like and, more particularly, to a method and apparatus for controlling the pressure and flow in water distribution networks.
The water distribution systems of waterworks include the complex distribution networks extended over a wide area. The present invention is intended to remotely operate the pumps and valves arranged on the distribution networks and thereby properly control the pressure and flow distribution in the distribution networks so as to ensure the service pressure for consumers and for preventing a high pressure which causes the leakage of water.
A number of methods have been proposed for controlling the distribution of water in waterworks. More particularly, in, for example, "Uniform Pressure Control in Water Distribution Networks", Sato, Journal of Japan Water Association, November, 1971, and "Program for Maintaining the Required Head at the Extremities of a Water Distribution Network", Ozawa, Mitsubishi Denki GiHo, September, 1980, systems are proposed respectively employing Newton's method and quadractic programming for obtaining the desired manipulated variables for controlling the pressure at the proper value.
Disadvantages of these proposed systems resides in the fact that the systems are incapable of correcting a difference between the estimation and actual measurement relating to the pressure and flow which might be caused if the control is effected by means of calculated manipulated variables. Moreover, a computation of the manipulated variables requires an excessive time and the systems cannot be used on an on-line basis.
The aim underlying the present invention essentially resides in over-coming the above-noted disadvantages of the the prior art by providing a control method and apparatus whereby manipulated variables or control amounts for properly controlling the pressures and flows are computed in such a short time so as to allow the system to be used on the on-line basis (less than five minutes) so that if, after the actual operation, the actual measured pressures and flows are still insufficient, the desired corrections for the control amounts are computed rapidly and the corrections are actually effected thereby always maintaining the proper pressures and flows.
In accordance with the present invention a method and apparatus is provided featuring a pressure/flow controller including a unit for computing optimum manipulated variables or a control amount optimum computing unit and a unit for correcting the control amounts in accordance with the actual measured values or a correction computing unit, with the optimum computing unit incorporating a network model simulating hydraulic phenomena within a distribution network so as to input the current total demand (the sum of the reservoir outlet flow rates) and thereby compute the optimum control amounts in a short time by high speed computation according to a network algorithm (see R. G. Busacher, T. L. Saaty: Finite Graph and Networks, McGraw-Hill, 1965), and with the correction computing unit utilizing a sensitivity matrix which indicates the effects of variations in the control amounts on the pressures and flows so as to compute control amount corrections and thereby correct the deviations from the estimated pressure and flow rate values.